HAP1 and sarcoma: Phenotypic variability associated with another variant in cis is exemplified by the presence of XAF1 p.E134∗ in a subset of TP53 p.R337H carriers (Hap1) that are at higher risk of cancer in general, sarcomas, and multiple tumors compared with those with TP53 p.R337H alone (Hap2).8